On Tue, 7 Apr 2009, Zhonggui Li wrote:

> But the transmission is quite slow so it's not acceptable for the server
> program. And it would be too much work to upgrade the libaries within the
> timeframe we have.

> Do you have any suggestions?

1. Stop top-posting. I'm starting to not respond to top-posters so if you want
    answers you (everyone!) need to follow the netiquette.

2. Consider using the multi interface as that allows multiple simultaneous
    uploads without using threads. And for SFTP you will want to use several
    upload connections for maximum performance.

3. If you want to remain multi-threaded, use the SSL library mutex callbacks.

4. If you want faster performance (and more stable operation) you upgrade
    libcurl and libssh2.

-- 
  / daniel.haxx.se